1. Field of the Invention
The present invention relates to methods for optimizing the speed of a spindle over an entire motion contour in a synchronous system. More specifically, optimizing the speed of a spindle within the limit of motion error of a synchronized component in a motion profile.
2. Background of the Invention
It is common in manufacturing and industrial processes of various types to move a first component synchronously with a second or plurality of components. One such common synchronous system includes a machine that moves a first component, such as a tool, synchronously with a rotating spindle having a part thereon. Machines of this type are commonly used for machining ophthalmic lenses. In such applications, the first component moves synchronously with the rotating spindle in order to follow contours on the part that are not rotationally symmetric with respect to the spindle. The motion profile of the first component, therefore, will have frequency components that depend on the rotational speed of the spindle.
It is often beneficial to rotate the spindle at its maximum speed in order to maximize throughput and efficiency of the machine. However, as the spindle speed increases, the intensity of the motion of the synchronized component (the tool) also increases. It is necessary then, to take into account the velocity, acceleration, and cut-off frequency constraints of the synchronized component as well as the maximum rotational speed of the spindle in order to optimize the motion profile.
As stated above, in general, it is beneficial to rotate the spindle as fast as possible without exceeding the velocity, acceleration, and cut-off frequency limit characteristics of the synchronized motion axis. Increasing the speed of the spindle presents a significant problem in that the motion error of the synchronized component increases as the spindle speed increases. Motion error is most commonly measured in terms of following error, dB gain error, phase lag and other components relating to the synchronized system. The motion error of the synchronized component must not exceed pre-defined requirements. If it were possible to estimate by calculation beforehand the motion error of a portion of the motion contour at a particular (selected) spindle speed, it would be possible to optimize the motion of that portion of the contour for both speed and accuracy. A need, therefore, exists when using a machine that moves a first component synchronously with a rotating spindle for a method of estimating the motion error of a portion of the motion contour at a particular spindle speed in order to optimize the motion of that portion of the contour for both speed and accuracy.
A second problem is that calculation of the optimum spindle speed through calculation beforehand of the motion error of a portion of the motion contour relates only to the specified portion of the motion contour. A need, therefore, also exists for a method for obtaining the optimum spindle speed across the entire motion contour.